Optimization of Cognitive MAC Frame Structure from an Energy Efficiency Perspective

Energy efficiency (EE) of wireless communications has attracted growing attention in recent years. In this paper, we focus on the EE optimization in cognitive radio networks (CRN) from a perspective of designing MAC frame structure, namely scheduling the sensing-then-transmission time slots. Considering secondary users adopting channel handoff to avoid collisions with primary users, the EE of CRN is modeled, which is a function of the sensing time and the transmission time. Under the constraint of protecting primary users sufficiently, an EE optimization problem is formulated, and the energy- efficient MAC frame is thus obtained by solving the problem. Simulation results confirm theoretical analysis, i.e., the EE of CRN depends on the sensing capability and interference constraint. Moreover, the proposed optimization method for cognitive MAC frame can enhance the EE of CRN effectively.